In present, in the field of refrigeration control technique, more and more evaporators start to employ micro-channel heat exchangers to improve the heat exchange efficiency. The micro-channel heat exchanger generally includes two sets of headers, multiple sets of flat tubes arranged between the two sets of headers, fins arranged between the flat tubes, side boards, and etc. After being throttled and depressurized by an expansion valve, the refrigerant becomes gas-liquid two-phase state and then enters into the headers to be distributed into flat tubes, in the process of the refrigerant being distributed into the flat tubes, an inhomogeneous distribution of refrigerant may be generated between each flat tube. More refrigerant flow may be distributed into the flat tubes near two ends of the headers. Meanwhile since the refrigerant is in gas-liquid two-phase state, the inhomogeneous distribution of the refrigerant may be further aggravated due to the layered phenomenon of the gaseous refrigerant and the liquid refrigerant. A metal introducing tube is generally inserted in the header as a distribution tube to ensure a homogenous distribution of refrigerant in each flat tube of the micro-channel heat exchanger. The tube is inserted to a bottom of the header with its end sealed, and meanwhile grooves or holes are formed with a certain distance on an arc surface of the tube along the length direction, thus via these holes or grooves, the refrigerant can be uniformly distributed into each flat tube for circulation. In a solution disclosed in FIG. 13, a micro-channel heat exchanger includes two sets of headers 1′, multiple sets of flat tubes 3′ arranged between the two sets of headers 1′ and fins arranged between the flat tubes 3′, a distributor 2′ is inserted into the header 1′, and fluid is distributed to the flat tubes via multiples small holes arranged in the distributor 2′. In another technical solution, such as the technical solution disclosed in US20080023185, a metal flat plate is inserted into a header to separate the header to two fluid passages, and meanwhile holes or grooves are formed with a certain distance on a lateral surface of the flat plate along the length direction, thereby realizing the homogeneous distribution and collection of the refrigerant.
In both the above two technical solutions, each hole is used for distributing refrigerant into flat tubes in one area, with one hole corresponding to multiple flat tubes, thus the refrigerant flowing from the holes is distributed again in partial areas. Since the fluid passing through the distributor is a two-phase fluid, noises may be caused when the two-phase fluid enters into the header, and noises may also be caused when the fluid enters into the flat tubes. For air conditioners with the evaporator placed indoor, such noises are difficult to be accepted by users. In addition, in the above two technical solutions, it is required to perforate the distributor or the flat plate which is to be inserted into the header, thus due to the perforation structure, the technology is complicated and the requirement of machining accuracy is high. Besides, the sizes and intervals of the flow areas of the holes are required to be constantly debugged while debugging the distribution homogeneity, resulting in an overly long development period and a relatively higher development cost of the evaporator.